The present invention relates generally to printing presses.
A 4 by 2 printing press, for example, provides for four printing plates across a plate cylinder and two printing plates around the circumference of the plate cylinder. Thus a total of eight images may be printed onto a web from one plate cylinder. The Uniliner double-wide press from Goss International for example may have such plate cylinders.
Such double-wide plate cylinders typically are at least forty six inches wide and may be for example forty inches in circumference or more. A plate cylinder for example may have fifty six inches in width and forty four inches in circumference.
These double-wide plate cylinders often have staggered plate lock-ups for the tail and lead edges of the printing plates, as shown in FIGS. 1 and 3 for plate cylinder 10. Since plate cylinder 10 fits two printing plates around the circumference of plate cylinder 10, for example printing plates 12 and 14, lock-ups at one axial location are 180 degrees apart, located at the lead and tail end of each printing plate 12, 14. A typical four wide plate cylinder will have a lock-up for two of the plates staggered 90 degrees with respect to a lock-up for two other plates spaced axially. This staggering improves balance in the cylinder and reduces vibration during printing. As shown in FIG. 3, a lock-up 30 for printing plates 12 and 14 on plate cylinder 10 is staggered 90° with respect to a lock-up 32 for printing plates 16, 18.
The four wide plate cylinder often is used to produce a regular tabloid or Broadsheet. A Berliner tabloid is a newspaper format with pages normally measuring about 470 mm×315 mm (18.5 in×12.4 in).